Cut-out for incandescent lamps and similar articles



Oct. 10, 1933. I R B. THMAs 1,930,326

CUT-OUT FOR INCANDESGENT LAMPS AND SIMILAR ARTICLES Filed April 23, 1931 INVENTUR RALPH E. ZTH'UMA s Patented Oct. 10, 1933 CUT-OUT FOR INCANDESCENT LAMPS AND SIMILAR ARTICLES Ralph B. Thomas, Cleveland Heights, Ohio, assignor to General Electric Company, a corporation of New .York

Application April 23, 1931. Serial No. 532,262 Claims. (01. 176 -24) My invention relates to cut-outs for series electric incandescent lamps and other similar electrical devices comprising a filament or other electric energy translation element mounted in 5 a glassenclosure such as a bulb. Such cut-outs operate upon failure of the said filament or other element to preserve the electric circuit so that the other devices in the circuit will continue tooperate. One object of my invention is to proed and which may be conveniently attached.

Another object is to provide a-cut-out which may be conveniently tested before attachment to the lamp or other device.

The cut-out of my invention is disc shaped and is provided with an aperture or a plurality of apertures through each of which extend one or more lead wires of the lamp or other device. To avoid wear, I prefer to have located in each of said apertures a metallic sleeve and to have the disc composed of a metallic oxide or preferably of metal coated with such oxide. I prefer. also to have an intermediate opening through said disc through which may extend the tip end of an arbor which may be the exhaust tube, when the device is located outside of the bulb or other glass enclosure, or a glass rod or cane used as part of the filament support if it is located within said enclosure. Other features and advantages of my invention will appear from the following description of species thereof and' from the accompanying drawing.

Inthe drawing Fig. l is a perspective view of an electric incandescent lamp in which is embodied one form of my invention; Fig.2 is a partial perspective view showing another form; Fig. 3 is a perspective view showing the cut-out parts. before assembly; andFig. 4 is a perspective view showing the cut-out in final form and position.

The electric incandescent lamp shown in Fig. 1 comprises the bulblO, base 11 and the mount comprising the glass stem 12, the leads 13, 14, which are sealed in said stem and are connected to the filament 15; The stem is of the type disclosed in Mitchell and White Patent No. 1,423,956 and comprises also the exhaust'tube 16 which communicates through aperture 17111 the solid or bulb. The lamp is evacuated or gas-filled through said exhaust tube which is subsequently tipped or sealed off. The cut-out proper .com-' -vide an eiTective cut-out which is securely mountseal portion of said stemwith the interior of the and the internal surfaces of said sleeves are coated with metallic oxide. Such oxide coating may I extend over all or part of the remainder of the disc and'may be the oxide of the disc metal. Such a coating may be formed as a film by oxidizing the metal of the disc. Bushings 23, 24 of metal are provided for the sleeves 21, 22 and these may have flanges 25, 26. Upon the insertion of said bushings into the sleeves, their unfianged ends may be given an oval form, the additional width in one direction serving to retain the bushings in the sleeves and the reduction of width in the transverse directionv serving to cause the bushing to grip the lead wire upon its insertion. This operation may be performed by the inserting of a tapered tool having an oval crosssection into the end of said bushing.

The disc 18 is provided with a. central opening or passage 27. In the form shown in Fig. 1, where the cut-out is located outside of the bulb, the tip end of the exhaust tube 16'serves as an arbor which extends through said opening and the disc rests on the flared end of the stem tube. In the form shown in Fig. 2, the cut-out is located inside the bulb and the glass rod or cane 28 serves as an arbor which extends through the said central opening.

In operation the cut-out will not function as long as the filament is intact as the oxide film acts as an insulator. When the filament fails the difference of voltage between the leads becomes high and-the oxide film breaks down thus providing a path for the current across the cutout disc. The cut-out may be assembled and tested out before mounting in the lamp.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In an electric device, the combination of a glass enclosure, an electric energy translation element mounted in said enclosure, leads extend ing into said enclosure and exteriorly thereof and a cut-out comprising a metal disc carrying a metallic compound and having passages through which said leads extend.

2. In an electric device, the combination of a 9 glass enclosure, an electric energy translation element mounted in said enclosure, leads extending into said enclosure and exteriorly thereof and a cut-out disc comprising a metallic conipound and having passages and metallic bushings therein through which said leads extend.

3. In an electric device, the combination of a glass enclosure, an electric energy translation element mounted in said enclosure, a glass stem comprising a longitudinally extending arbor and 5. In an electric device, the combination of a glass enclosure, an electric energy translation element mounted in said enclosure, leads extending into said enclosure and exteriorly thereof and a cut-out disc comprising a metallic compound and having passages and metallic bushings therein in close electrical contact with said disc and with said leads and surrounding the latter.

RALPH B. THOMAS. 

